Win - No enemy or enemy invasions are left
Lose - Your lord dies
This mission will rely completely on the army you raised in mission 1. You will be attacked in waves and thus need to act fast. Remove all of Edwin’s resource buildings, including the granary. Your land should be completely clean except for castle walls, towers, the barracks, and the armoury. Place a market and buy a lot of stone. You will need to repair the walls you destroyed, then build a second wall in front of the main one with 2 bastion towers on either side. Make sure your crossbowmen and archers are in the main tower to hold back enemy knights until the walls are sealed off. Once your defences are complete, move the crossbowmen and archers into all the different towers and the gatehouse.
The image above shows my defence for this mission. I had 40 crossbowmen in each bastion with 20 archers. The big tower had a mix of crossbowmen and archers, and the gatehouse the same. I also built a small third wall right next to the barracks as a last line of defence. I also used the 200 pitch given to you at the start of this mission as extra defence. Remember to place braziers in the archer towers to light these. As you can see, the catapults are adjacent to the keep. If worst comes to worst, you can use the manual targeting mechanic to hold off enemy units from reaching the keep. If you defended well, you will not need these.
Once the main invasion begins, you need discipline. As soon as you see the ballistae and the trebuchets, it is normal to want to retreat your ranged units. Do not do this. Your first wall will take the brunt of the force. Any units that are shot off the towers should be retreated to the second wall. Do not send them back up to their original towers. The mass number of crossbowmen should succeed in preventing ladders being placed on your walls. This will cause melee units to stand around doing nothing as your troops fire bolts and arrows into them. It is likely the first wall will eventually be breached. If this happens, be ready to light the pitch and use the burning logs. Once your first wall and towers are empty, you can remove it to prevent enemy units using them as cover. This will allow your ranged units to attack them continuously. Once the final unit is killed, you will complete the mission and be given a choice as to what side you wish to follow. Do not fear, you will be able to complete the missions for either side no matter which you choose. Good job!